JP7201356B2 - Position determination device and position determination system - Google Patents

Description

The present invention relates to a position determination technique based on received power of radio signals.

In recent years, BLE (Bluetooth Low Energy), which is one of extended specifications of Bluetooth (registered trademark), is used to detect the position of a BLE transmitter (also called a beacon) or a BLE receiver. For example, based on the received power of a BLE signal (also called a beacon signal) transmitted by the BLE transmitter, it is possible to determine which of the multiple BLE receivers the BLE transmitter is near, and so on.

Patent Document 1 describes determining RSSI quality based on RSSI (Received Signal Strength Indication) and calculating directional characteristics D of a mobile terminal based on the RSSI quality. Also, in Patent Document 1, when the RSSI quality is bad, the mobile terminal user turns his back to the beacon node, and when the RSSI quality is good, the mobile terminal user turns to the beacon node. There is also a description of Furthermore, Patent Document 1 expresses the RSSI as a function of the environmental factors A and n and the distance between the mobile terminal and the beacon node. It is also stated that the smaller [A,n], the better the RSSI quality. Patent Document 1 describes extracting movement characteristic information including this directional characteristic D, and based on this, calculating the movement characteristic probability for the restricted area of the mobile terminal.

Patent Literature 2 describes that even if a person stands at the same position, the intensity of received radio waves varies depending on the orientation of the person's body and the way the receiver is held. Further, in Patent Literature 2, the server 4 has a plurality of ways of holding the receiver 3 by a person 10 of each receiver 3, or ways of holding the receiver 3 by a person 10 of each receiver 3, or ways of holding the receiver 3 by a person 10 and the position of the receiver 3 are appropriately selected according to the combination of the directions of the receiver 3 and the position of the receiver 3 .

JP-A-2017-37076 ([0052] to [0053], [0062], [0064] to [0065], [0072], [0096] to [0097]) JP 2017-201240 A ([0007], [0043], [0062])

When actually performing position determination using BLE, fading due to interference between the direct wave of the beacon signal and the reflected wave (for example, from the ground) becomes a problem. Specifically, as the propagation distance of the beacon signal increases, the divergence between the measured RSSI value and the theoretical curve of RSSI versus distance increases due to the effects of multipath. Accuracy can be reduced. Furthermore, even with a theoretical curve, the longer the distance, the smaller the change in RSSI with respect to the change in distance, making it difficult to accurately estimate the distance from the RSSI.

Given these problems, to achieve practical accuracy in conventional positioning systems, either receivers or transmitters had to be densely spaced in close proximity to each other, on the order of 3m or less. .

Although Patent Documents 1 and 2 do not provide a sufficient explanation of how beacon nodes and grids can be specifically arranged, similar restrictions are imposed in view of the lack of mention of countermeasures against fading. expected to be

Therefore, due to this arrangement constraint, for example, when building a conventional position determination system on the road in front of the entrance of a facility, if the width of the road exceeds about 6 m, it is not possible to simply install a receiver (or transmitter) on the side of the road. When the transmitter (or receiver) is located near the center of the road, it becomes difficult to determine the position with practical accuracy. Therefore, problems such as having to install a receiver (or transmitter) near the center of the road due to burying work or arches may occur.

An object of the present invention is to relax the placement restrictions of receivers or transmitters installed in a position determination system.

According to one aspect of the present invention, a position determination device includes a receiver, an estimator, and a determiner. (a) receiving power of said radio signal from a plurality of first receivers installed at a first position and receiving the radio signal transmitted by the target transmitter; (b) said plurality of second receivers of said wireless signals from a plurality of second receivers located at a second location and receiving said wireless signals; receive a second set of received power data representative of received power at . The estimating unit estimates the received power of the radio signal at the first position based on the first received power data group to generate a first estimated value, and generates a first estimated value based on the second received power data group. to estimate the received power of the radio signal at the second location to generate a second estimate. The determining unit uses the first estimated value, the second estimated value, a first threshold, and a second threshold smaller than the first threshold to determine whether the target transmitter is at the first position. It is determined whether or not the line exists on the side of the second position from the line defined based on the above.

According to another aspect of the invention, a position determination device includes a receiver, an estimator, and a determiner. (a) receiving power of said radio signal from a plurality of first receivers installed at a first position and receiving the radio signal transmitted by the target transmitter; (b) said plurality of second receivers of said wireless signals from a plurality of second receivers located at a second location and receiving said wireless signals; (c) said plurality of third receivers of said wireless signals from a plurality of third receivers located at a third location and configured to receive said wireless signals; (d) from a plurality of fourth receivers located at a fourth location and receiving said wireless signals from said plurality of said wireless signals; receiving a fourth set of received power data representative of received power at a fourth receiver of . The estimating unit estimates the received power of the radio signal at the first position based on the first received power data group to generate a first estimated value, and generates a first estimated value based on the second received power data group. estimating the received power of the radio signal at the second position to generate a second estimated value, and estimating the received power of the radio signal at the third position based on the third group of received power data estimating to generate a third estimate; and estimating the received power of the radio signal at the fourth location based on the fourth set of received power data to generate a fourth estimate. The determination unit determines the first estimated value, the second estimated value, the third estimated value, the fourth estimated value, the first threshold, and the second threshold smaller than the first threshold. determining whether the target transmitter is on the third or fourth position side of a line defined based on the first and second positions using do.

ADVANTAGE OF THE INVENTION According to this invention, the arrangement|positioning restrictions of the receiver or transmitter installed in a position determination system can be eased.

1 is a block diagram illustrating a position determination device according to an embodiment; FIG. FIG. 2 illustrates a position determination system including the position determination device of FIG. 1; FIG. 3 is a diagram illustrating the beacon receiver of FIG. 2; 4 is a graph illustrating temporal variation of received power in a beacon receiver; 4 is a graph illustrating the relationship between the distance from a beacon transmitter to a beacon receiver and received power; The figure which illustrates the electric wave shielding effect by a human body. FIG. 4 is an explanatory diagram of two threshold values used for position determination of a beacon; 6 is a graph illustrating changes in received power at each position before and after a user wearing a beacon transmitter passes the passage determination line; 2 is a flowchart illustrating the operation of the position determination device of FIG. 1; FIG. 10 is a flowchart illustrating details of step S410 in FIG. 9; FIG. FIG. 10 is a flowchart illustrating some details of step S420 of FIG. 9; FIG. FIG. 10 is a flowchart illustrating details of the remainder of step S420 of FIG. 9; FIG. FIG. 5 is a diagram illustrating changes in received power at each position before and after a user wearing a beacon transmitter passes through a passage determination line, and position determination results at each time point;

An embodiment will be described below with reference to the drawings. Elements that are the same as or similar to elements that have already been explained are denoted by the same or similar reference numerals, and overlapping explanations are basically omitted. For example, when there are a plurality of identical or similar elements, common reference numerals may be used to describe each element without distinction, and the common reference numerals may be used to distinguish and describe each element. In addition, branch numbers are sometimes used.

(embodiment)
The position determination device according to the embodiment can be incorporated into the position determination system shown in FIG. 2, for example. This position determination system includes a position determination device 100 according to the embodiment and four beacon receivers 200-A1, 200-A2, 200-C1 and 200-C2. Each of the four beacon receivers 200 includes multiple beacon receivers as described below.

The branch number (suffix) of the code of each beacon receiving device 200 represents the installation position of the beacon receiving device 200 . Also, the position A1 and the position A2 define a passage determination line, which will be described later, and the passage determination line can be defined as a straight line passing through the position A1 and the position A2, for example.

In the example of FIG. 2, the positions A1, A2, C1 and C2 are determined to correspond to the vertices of a rectangle with a width of 10 m and a depth of 5 m. That is, according to this position determination system, if the road is an outdoor road with a width of up to about 10 m, it is not necessary to install the beacon receiver 200 near the center of the road. The possibility of such an arrangement is supported by the fact that the distance between the beacon transmitter and the beacon receiver 200 can be estimated with high accuracy up to about 5 m in this embodiment, as will be described later. be done.

The beacon transmitter is, for example, a nameplate type device, and is worn by the user 300 of the beacon transmitter by hanging it around the neck or fastening it to the chest. The following description basically assumes that the beacon transmitter is worn on the front side of the user 300 .

It should be noted that "beacon," "beacon transmitter," and "beacon receiver" are merely exemplary designations. "Beacon" can be read as "radio signal", "beacon transmitter" can be read as "wireless) transmitter", "beacon receiver (or receiver)" can be read as "(wireless) receiver (or receiver)", etc. .

Beacon transmitters are prohibited from being taken out from positions C1 and C2 with respect to the passage determination line. On the other hand, the side opposite to positions C1 and C2 with respect to the passage determination line is an area where carrying around of the beacon transmitter is permitted (hereinafter referred to as permitted area).

Based on the received power data from the plurality of beacon receivers included in each beacon receiver 200, the position determination device 100 determines at least whether or not the user 300 possessing the beacon transmitter has passed the passage determination line. Specifically, it is determined whether or not the beacon transmitter exists on the position C1 or C2 side of the passage determination line.

The beacon receiver 200 includes two beacon receivers 210-1 and 210-2, a pole 220, and a base 230, as illustrated in FIG. In the example of FIG. 3, one beacon receiver 200 includes two beacon receivers 210, so if the beacon receivers 200 are installed at four locations, the position determination device 100 can receive a total of eight beacons. Received power data can be obtained from machine 210 .

Beacon receiver 210-1 and beacon receiver 210-2 are attached to pole 220 with an interval of at least half the wavelength of the beacon signal from each other. A space diversity effect can be obtained by such a configuration and the reception power estimation processing described later in the position determination device 200 . Here, the half wavelength of the beacon signal corresponds to, for example, a little over 6 cm in the case of the BLE signal.

In the example of FIG. 3, beacon receiver 210-1 and beacon receiver 210-2 are mounted on pole 220 spaced apart from each other by at least half the wavelength of the beacon signal along the vertical direction, that is, along the longitudinal direction. It is Such an arrangement is suitable for environments, such as outdoors, where fading occurs mainly due to interference between the direct wave of the beacon signal and the reflected wave mainly from the ground or floor.

On the other hand, in an environment such as indoors where reflected waves from walls also exist, beacon receivers 210-1 and 210-2 are separated not only in the vertical direction but also in the horizontal direction, that is, in the direction orthogonal to the vertical direction. It may be placed open. Alternatively, installing the beacon receiver 200 near a wall is also effective in reducing fading caused by interference between the direct wave and the reflected wave from the wall.

Note that the number of beacon receivers 210 included in one beacon receiver 200 may be three or more. For example, four beacon receivers 210 may be mounted on a pole 220 to correspond to the vertices of a square whose sides are at least half the wavelength of the beacon signal.

Beacon receiver 210 may include, for example, a BLE receiver and a Sub-GHz band communicator. A combination of such a BLE receiver and a Sub-GHz band communication device is also called a BLE to Sub-GHz Gateway.

A BLE receiver receives a BLE signal as a beacon signal and generates received power data, eg, RSSI data. Then, the BLE receiver sends the reception power data to the Sub-GHz band communication device via HCI (Host Controller Interface). Note that the received power data may include an identifier for identifying the BLE receiver and an identifier for identifying the beacon transmitter that is the transmission source of the beacon signal, in addition to data representing the value of the received power, such as RSSI.

As a host, the Sub-GHz band communication device acquires received power data from the BLE receiver via HCI. The Sub-GHz band communication device converts this into a radio signal for Sub-GHz band communication and transmits it to the position determination device 100 .

Pole 220 is attached to and supports beacon receiver 210-1 and beacon receiver 210-2. Also, the base 230 supports the pole 220 .

Position determination device 100 includes reception section 101, reception power log storage section 102, reception power estimation section 103, position determination section 104, and alarm section 105, as illustrated in FIG. Position determining device 100 may be a PC (Personal Computer) or other computer.

Position determination device 100 may include, as hardware elements, part or all of, for example, a processor, memory, auxiliary storage device, communication interface, input/output interface, input device, and output device. Also, each hardware element may be connected to each other via a bus, for example.

The processor implements various processes described later by executing programs. The processor is typically a CPU (Central Processing Unit) and/or a GPU (Graphics Processing Unit), but may be a microcomputer, an FPGA (Field Programmable Gate Array), or a DSP (Digital Signal Processor). .

The memory may temporarily store programs executed by the processor and data used by the processor. The memory may include a RAM (Random Access Memory) having a work area in which such programs/data are deployed. The auxiliary storage device can be, for example, a HDD (Hard Disc Drive), an SSD (Solid State Drive), a flash memory, or the like.

The communication interface is a module for communicating with an external device, for example, a plurality of beacon receivers included in the beacon receiving device 200, and includes a signal processing circuit for transmission and reception, an antenna, a LAN (Local Area Network) terminal, and the like. can contain. The communication interface can be, for example, a module for Sub-GHz radio, a module for wireless LAN, a module for wide area communication such as mobile communication, and the like.

The input/output interface is a USB (Universal Serial Bus) terminal, a terminal for other data transfer cables, or the like. Also, the output device is a display, a speaker, or the like.

The receiving unit 101 can be realized by the communication interface described above. The receiving unit 101 receives received power data groups from a plurality of beacon receivers included in the beacon receiving device 200 . The received power data group represents the received power of a beacon signal transmitted by a beacon transmitter at a plurality of beacon receivers.

Received power log storage unit 102 can be realized by the aforementioned memory and/or auxiliary storage device. The received power log storage unit 102 stores the received power data group acquired by the receiving unit 101 . The reception power data group can be read by reception power estimation section 103 as necessary.

Here, each reception power data included in the reception power data group is, for example, an identifier that identifies the beacon receiver that is the source of the reception power data and an identifier that identifies the beacon transmitter that is the transmission source of the beacon signal (or (identifier of user 300) and stored in received power log storage unit 102. FIG.

Received power estimating section 103 can be realized by the aforementioned processor and memory. Received power estimation section 103 reads out the received power data group corresponding to each beacon receiving device 200 from received power log storage section 102 . Based on the read received power data group, received power estimation section 103 estimates the received power of the beacon signal at the installation position of beacon receiving apparatus 200 to which beacon receiver 210 corresponding to the received power data group belongs. , to generate an estimate of the received power of the beacon signal at that location. When beacon receivers 200 are installed at four locations as shown in FIG. 2, received power estimation section 103 generates four estimated values. The received power estimator 103 sends the estimated value of the received power of the beacon signal at each position to the position determiner 104 .

Details of the processing performed by received power estimation section 103 will be described below.
Specifically, for each position, for each beacon receiver 210 of the beacon receiving device 200 installed at that position, the received power estimation unit 103 calculates the most recent received power data from the received power data corresponding to the beacon receiver 210. The maximum value of the received power over time is searched, and the offset corresponding to the beacon receiver 210 is added to calculate one of the candidate values of the received power of the beacon signal at that location. That is, received power estimation section 103 calculates a plurality of candidate values (candidate value group) for each position. Here, the offset is a correction value for absorbing the characteristic difference between beacon receivers 210 and is determined for each beacon receiver 210 .

The received power at the beacon receiver 210 fluctuates (fluctuations) over time as illustrated in FIG. 4 even if the beacon receiver 210 is in a stationary state. Therefore, by searching for the maximum value of received power over a period of time longer than one cycle of such fluctuations, the influence of fluctuations in received power in each beacon receiver 210 can be suppressed.

Received power estimating section 103 then determines the maximum value of the candidate value group at each position as the estimated value of the received power of the beacon signal at that position. In other words, received power estimating section 103 calculates the maximum value of the candidate values calculated for a plurality of beacon receivers 210 included in each beacon receiving device 200 according to the reception of the beacon signal at the position where the beacon receiving device 200 is installed. Determined as an estimate of power.

FIG. 5 shows the theoretical curve of distance vs. RSSI, the actual measurement results of two beacon receivers 1 and 2 arranged in the same manner as beacon receivers 210-1 and 210-2, and the actual measurement results for each measurement point. and the result of connecting the maximum values. The actual measurement results of the beacon receivers 1 and 2 are obtained by plotting the RSSI in the beacon receivers 1 and 2 when the beacon signal is transmitted outdoors every 1 m. Further, the actual measurement results of the beacon receivers 1 and 2 can ignore the influence of fluctuation because the above-described fluctuation countermeasures are taken.

A theoretical curve of distance versus RSSI in free space can be obtained by the Friis transfer formula. However, in practice, this theoretical curve may not hold true not only at long distances where the influence of multipath is great, but also at short distances. For example, for the receiver 1, the actual measurement result at a distance of 3 m, which can be said to be a short distance, is about 4 dBm below the theoretical curve, and the estimated distance based on this RSSI alone is about 5 m, resulting in an error of about 2 m. On the other hand, for the receiver 2, although the actual measurement result closer to the theoretical curve than the receiver 1 was obtained up to a distance of about 11 m, the actual measurement result at a distance of 12 m was about 10 dBm lower than the theoretical curve.

As can be read from FIG. 5, the beacon receivers 1 and 2 have different RSSI drop patterns. Therefore, fading can be reduced by adopting the maximum value of both as the estimated value of received power (spatial diversity effect). As a result, the polygonal line connecting the maximum values of the actual measurement results of the beacon receivers 1 and 2 for each measurement point was close to the theoretical curve up to a distance of about 5 m. On the other hand, it can be seen that the effect of fading is partially seen in the distance range of 5 to 10 m, and is only 10 m or more when the distance is 10 m or more.

Therefore, by determining the maximum value of the candidate values calculated for the plurality of beacon receivers 210 included in each beacon receiver 200 as the estimated value of the received power of the beacon signal at the position where the beacon receiver 200 is installed, , the distance can be estimated with high accuracy up to about 5 m, and even if the distance is greater than 5 m, it is not possible to determine whether it is in the range of about 5 m to 10 m or 10 m or more. It is possible.

The position determination unit 104 can be realized by the aforementioned processor and memory. The position determination unit 104 determines the position of the beacon transmitter using the estimated value of the received power of the beacon signal at each position and the first and second thresholds described later. For example, the position determination unit 104 determines the position of the beacon transmitter from any of a plurality of labels including at least "outside the gate" which means that the beacon transmitter exists on the position C1 or position C2 side of the passage determination line. It is judged as Position determination section 104 sends the determination result to alarm section 105 .

A first threshold may correspond to a reference value for determining whether a beacon transmitter is in proximity to the beacon receiver 200 . As described above, in this embodiment, the distance can be estimated with high accuracy up to a distance of about 5 m, so proximity can be defined as the distance being equal to or less than the upper limit of 5 m or less. For example, if the upper limit value is 4 m in the example of FIG. 5, the first threshold can be set at about -58 dBm as illustrated in FIG.

On the other hand, the second threshold may correspond to a reference value for determining whether the distance between the beacon transmitter and the beacon receiver 200 exceeds the detection limit distance. As described above, in this embodiment, it is only known that the distance is 10 m or more, so the detection limit distance can be defined as 10 m or a smaller value. For example, if the detection limit distance is 10 m in the example of FIG. 5, the second threshold can be set to about -66 dBm as illustrated in FIG.

Also, as mentioned above, the beacon transmitter is worn on the front side of the user 300 . Radio waves in the frequency band of 2.4 GHz, such as BLE signals, have the property of being highly rectilinear and being easily absorbed by water. Since about 70% of the human body is water, the radio waves emitted from the beacon transmitter are absorbed by the body of the user 300 and are hardly circulated. Therefore, the transmission power of the beacon signal is greatly attenuated behind the user 300, as illustrated in FIG. This attenuation exceeds 10 dBm. That is, before and after the user 300 passes the passage determination line, attenuation exceeding 10 dBm occurs at the positions A1 and A2.

FIG. 8 shows positions A1, A2, C1, and C2 from the permitted area until the user wearing the beacon transmitter passes the passage decision line and finally also the line connecting positions C1 and C2. Fig. 3 illustrates the change in received power at C2;

According to FIG. 8, the received powers at positions A1 and A2 begin to decrease sharply from around measurement count 33, while the received powers at positions C1 and C2 level off or increase. This suggests that the user is about to pass the pass determination line. At this time, the received power at locations A1 and A2 will fall below the first threshold and possibly the second threshold even though they are actually in close proximity to the beacon transmitter. .

Also, from around measurement count 49, the received power at positions C1 and C2 begins to decrease sharply. This suggests that the user will eventually pass the line connecting positions C1 and C2. At this time, the received power at locations C1 and C2 will fall below the first threshold and possibly the second threshold even though they are actually close to the beacon transmitter. .

The position determination unit 104 performs position determination as follows, using the drop in received power due to the radio wave shielding effect of the human body.
(1) If the estimated value at position A1 or position A2 is greater than or equal to the first threshold, then the beacon transmitter is close to position A1 or position A2 and the body of user 300 is at position A1 or position A2. expected to be suitable for And further, if the estimated value at location A1 is greater than or equal to the estimated value at location C1, or the estimated value at location A2 is greater than or equal to the estimated value at location C2, then the beacon transmitter is located at location A1 or at location C2 rather than at location C1 or location C2. It is expected to be close to A2. Therefore, the position determination unit 104 determines the position of the beacon transmitter as, for example, "on the line", which means that the beacon transmitter exists in the vicinity of the passage determination line, or on the near side of the passage determination line, that is, in the permitted area. It can be determined as "within the gate", which means that Note that "on the line" and "inside the gate" do not necessarily have to be distinguished, and for example, "on the line" may be integrated into "inside the gate". On the other hand, the position determination unit 104 determines that the estimated value at position A1 is greater than or equal to the first threshold but less than the estimated value at position C1, or the estimated value at position A2 is greater than or equal to the first threshold but less than the estimated value at position C2. In the case of , the position of the beacon transmitter, for example, the beacon transmitter has already passed the passage determination line, that is, the beacon transmitter exists on the position C1 or position C2 side of the passage determination line. It can be judged as "outside".

(2) If the estimated values at location A1 and location A2 are both less than the first threshold and the estimated values at location C1 or location C2 are greater than or equal to the first threshold, then the beacon transmitter determines location Proximity to C1 or position C2, and the body of user 300 is expected to face position C1 or position C2, in other words, back to position A1 and position A2. Therefore, the position determining unit 104 can determine the position of the beacon transmitter to be "outside the gate".

(3) If the estimates at location A1, location A2, location C1, and location C2 are all less than a second threshold, then (a) the beacon transmitter is within the permitted area, but the location from the beacon transmitter; The distances to A1 and location A2 both exceed the distance corresponding to the second threshold, for example 10 m, (b) the beacon transmitter is within the permitted area, but the user 300 is behind location A1 and location A2; (c) the beacon transmitter is outside the permitted area, but the distances from the beacon transmitter to position C1 and position C2 both exceed a distance corresponding to a second threshold, e.g., 10 m; (d) The beacon transmitter is outside the permitted area, but the user 300 may have his back to position C1 and position C2, and so on. That is, if the estimated values at positions A1, A2, C1, and C2 are all less than the second threshold, it is determined whether or not the beacon transmitter exists within the permitted area based only on the estimated values. It is not possible. Therefore, the position determination unit 104 can determine the position of the beacon transmitter as "out of range", which means that the beacon transmitter exists outside the range in which the position can be determined.

Near the midpoint between positions A1 and A2 and near the midpoint between positions C1 and C2, the estimated values at these positions may be less than the first threshold and greater than or equal to the second threshold. Even in such a case, the position determination unit 104 can determine whether or not the beacon transmitter exists within the permitted area.

(4) the estimated values at the positions A1 and A2 are less than the first threshold and equal to or greater than the second threshold, the estimated value at the position A1 is greater than or equal to the estimated value at the position C1, and the estimated value at the position A2 is If it is greater than or equal to the estimated value at position C2, it means that the beacon transmitter is near the midpoint between positions A1 and A2, and the body of user 300 is facing either position A1 or position A2. there is Therefore, the position determination unit 104 can determine the position of the beacon transmitter as, for example, "inside the gate".

(5) the estimated values at positions C1 and C2 are less than the first threshold and equal to or greater than the second threshold, the estimated value at position C1 is greater than or equal to the estimated value at position A1, and the estimated value at position C2 is If it is greater than or equal to the estimate at position A2, then the beacon transmitter is near the midpoint between positions C1 and C2, and the body of user 300 is facing either position C1 or position C2, in other words position It means that the back is turned to A1 and position A2. Therefore, the position determining unit 104 can determine the position of the beacon transmitter to be "outside the gate".

The alarm unit 105 can be implemented by a combination of the processor and memory described above, a communication interface, an input/output interface, and/or an output device. The alarm unit 105 issues an alarm when the determination result from the position determination unit 104 is, for example, "outside the gate". For example, the alarm unit 105 outputs "Abduction has occurred!", "Beacon XX is being taken away!" □ is going to take the beacon away!" may be sent to any terminal.

The operation of the position determination device 100 in FIG. 1 will be described below with reference to FIG. The operation of FIG. 9 can be performed, for example, every transmission period of the beacon signal.
First, the received power estimation unit 103 reads out the received power data group from the received power log storage unit 102, and estimates the received power of the beacon signal at each position based on this (step S410). Details of step S410 will be described later with reference to FIG.

Next, the position determination unit 104 determines the position of the target beacon based on the estimated received power of the beacon signal at each position generated in step S410 and the first and second thresholds ( step S420). The details of step S420 will be described later with reference to FIGS. 11 to 13. FIG.

If the determination result in step S420 is "outside the gate", the process proceeds to step S442, and if the determination result in step S420 is not "outside the gate", the operation of FIG. 9 ends (step S441).

In step S442, the alarm unit 105 outputs an alarm. Specifically, the alarm unit 105 may display or output a message by voice, and may transmit such message data to the administrator's terminal. After step S442, the operation of FIG. 9 ends.

Details of step S410 will be described below with reference to FIG. After starting step S410, the process first proceeds to step S411.
In step S411, received power estimation section 103 selects one of the unprocessed positions, and the process proceeds to step S412. According to the example of FIG. 2, the received power estimating unit 103 sequentially selects one from position A1, position A2, position C1 and position C2, and calculates the received power of the beacon signal at the selected position through steps S412 to S417. will be estimated.

In step S412, the received power estimation unit 103 selects one of the unprocessed beacon receivers 210 for the selected position. According to the example of FIG. 3, received power estimating section 103 sequentially selects one by one from beacon receiver 210-1 and beacon receiver 210-2 included in beacon receiving device 200 installed at the selected position, and step Through S413 to step S415, one of the received power candidate values of the beacon signal at the selected position is calculated.

The received power estimation unit 103 extracts the latest four RSSIs of the beacon receiver 210 selected in step S412 from the received power data group (step S413). Then, received power estimation section 103 searches for the maximum value of the four RSSIs extracted in step S413 (step S414). This makes it possible to suppress the influence of fluctuations in the received power of the beacon receiver 210 selected in step S412.

Furthermore, the received power estimating unit 103 adds the offset corresponding to the beacon receiver 210 selected in step S412 to the maximum RSSI searched in step S414 to calculate the candidate value corresponding to the beacon receiver 210 (step S415). Thereby, the characteristic difference between the beacon receivers 210 can be absorbed.

After completing step S415, the reception power estimation unit 103 determines whether or not there remains an unprocessed beacon receiver 210 for the selected position (step S416). If unprocessed beacon receivers 210 remain, the process returns to step S412, and if all beacon receivers 210 have been processed for the selected position, the process proceeds to step S417. According to the example of FIG. 3, the number of beacon receivers 210 for each position is two, so the determination results in step S416 are "Yes" and "No" in that order.

In step S417, the received power estimator 103 estimates the maximum value of candidate values for all beacon receivers 210 related to the selected position as the received power of the beacon signal at the selected position.

After step S417 is completed, received power estimation section 103 determines whether or not an unprocessed position remains (step S418). If unprocessed positions remain, the process returns to step S411, and if all positions have been processed, step S410 illustrated in FIG. 10 ends. According to the example of FIG. 2, since the number of positions is four, the determination results in step S418 are "Yes", "Yes", "Yes", and "No" in that order.

The details of step S420 will be described below with reference to FIGS. 11 to 13. FIG.
First, the position determination unit 104 determines whether or not all estimated values at the positions A1, A2, C1 and C2 are less than the second threshold Th2 (step S421). If it is determined that all of the estimated values at the positions A1, A2, C1 and C2 are less than the second threshold Th2, the process proceeds to step S422, where the positions A1, A2, C1 and C2 is equal to or greater than the second threshold Th2, the process proceeds to step S423.

In step S422, the position determination unit 104 determines that the position of the beacon transmitter is "out of range", and step S420 illustrated in FIGS. 11 and 12 ends.

In step S423, the position determination unit 104 determines whether or not the estimated value at the position A1 or the position A2 is greater than or equal to the first threshold Th1. If it is determined that the estimated value at the position A1 or the position A2 is equal to or greater than the first threshold Th1, the process proceeds to step S426, and it is determined that the estimated values at the positions A1 and A2 are all less than the first threshold Th1. If so, the process proceeds to step S424.

At step 424, the position determination unit 104 determines whether or not the estimated value at the position C1 or the position C2 is equal to or greater than the first threshold Th1. If it is determined that the estimated value at the position C1 or the position C2 is equal to or greater than the first threshold Th1, the process proceeds to step S425, and it is determined that the estimated values at the positions C1 and C2 are all less than the first threshold Th1. If so, the process proceeds to step S431 in FIG.

In step S425, the position determination unit 104 determines that the position of the beacon transmitter is "outside the gate", and step S420 illustrated in FIGS. 11 and 12 ends.

In step S426, the position determination unit 104 determines whether the estimated value at the position A1 is equal to or greater than the first threshold Th1 and exceeds the estimated value at the position C1, and whether the estimated value at the position A2 is equal to or greater than the first threshold Th. exceeding the estimated value at position C2 are satisfied. If at least one is determined to be satisfied, the process proceeds to step S427; otherwise, the process proceeds to step S428.

In step S427, the position determination unit 104 determines that the position of the beacon transmitter is "inside the gate", and step S420 illustrated in FIGS. 11 and 12 ends.

In step S428, the estimated value at position A1 is greater than or equal to the first threshold Th1 and substantially equal to the estimated value at position C1, and the estimated value at position A2 is greater than or equal to the first threshold Th1 and equals to the estimated value at position C2. It is determined whether at least one of approximately equal is satisfied. If it is determined that at least one is satisfied, the process proceeds to step S429, and if it is determined that both are not satisfied, the process proceeds to step S430.

In step S429, the position determination unit 104 determines that the position of the beacon transmitter is "on line", and step S420 illustrated in FIGS. 11 and 12 ends.

In step S430, the position determining unit 104 determines that the position of the beacon transmitter is "outside the gate", and step S420 illustrated in FIGS. 11 and 12 ends.

In step S431, the position determination unit 104 determines whether both the estimated value at position A1 exceeds the estimated value at position C1 and the estimated value at position A2 exceeds the estimated value at position C2 are satisfied. judge. If it is determined that both are satisfied, the process proceeds to step S432, and if it is determined that at least one is not satisfied, the process proceeds to step S434.

In step S432, the position determination unit 104 determines whether or not the estimated values at the positions A1 and A2 are greater than or equal to the second threshold Th2. If it is determined that the estimated values at the positions A1 and A2 are equal to or greater than the second threshold Th2, the process proceeds to step S433, and it is determined that the estimated values at the position A1 or the position A2 are less than the second threshold Th2. Otherwise, the process proceeds to step S437.

In step S433, the position determination unit 104 determines that the position of the beacon transmitter is "inside the gate", and step S420 illustrated in FIGS. 11 and 12 ends.

In step S434, the position determination unit 104 determines whether both the estimated value at position C1 exceeds the estimated value at position A1 and the estimated value at position C2 exceeds the estimated value at position A2 are satisfied. judge. If it is determined that both are satisfied, the process proceeds to step S435, and if it is determined that at least one is not satisfied, the process proceeds to step S437.

In step S435, the position determination unit 104 determines whether or not the estimated values at the positions C1 and C2 are greater than or equal to the second threshold Th2. If it is determined that the estimated values at the positions C1 and C2 are equal to or greater than the second threshold Th2, the process proceeds to step S436, and it is determined that the estimated values at the position C1 or the position C2 are less than the second threshold Th2. Otherwise, the process proceeds to step S437.

In step S436, the position determining unit 104 determines that the position of the beacon transmitter is "outside the gate", and step S420 illustrated in FIGS. 11 and 12 ends.

In step S437, the position determination unit 104 determines that the position of the beacon transmitter is not "out of range" but is "hold", which means that it cannot be concluded that it is "inside the gate" or "outside the gate", Step S420 illustrated in FIGS. 11 and 12 ends.

FIG. 13 shows positions A1, A2, C1, and C2 from the permitted area until the user wearing the beacon transmitter passes the passage decision line, and finally also the line connecting positions C1 and C2. Fig. 2 shows changes in received power at C2 and determination results of position determination section 104 at each time point. In the example of FIG. 13, the subject walked over a distance of over 10 meters in over 5 minutes in order to collect data at multiple points to determine position. In the example of FIG. 13, the first threshold Th1 and the second threshold Th2 are set to -58 dBm and -66 dBmm, respectively.

For example, the estimated values of the received power (RSSI) of the beacon signals at positions A1, A2, C1 and C2 at "14:55:25" in FIG. "-62 dBm" and "-61 dBm". Therefore, the position determination unit 104 performs the processing in order of steps S421, S423, S424, S431, S432, and S433, and obtains a determination result of "within the gate".

In addition, the estimated values of the received power (RSSI) of the beacon signals at the positions A1, A2, C1 and C2 at "14:57:02" in FIG. "-60 dBm" and "-55 dBm". Therefore, the position determination unit 104 executes the processing in order of steps S421, S423, S424, and S425, and obtains the determination result of "outside the gate".

As described above, the position determination device according to the embodiment uses the spatial diversity effect to highly accurately estimate received power corrected for dips due to fading for a plurality of positions. A size comparison using a threshold value is performed to determine the position of the beacon transmitter. Specifically, the position determination device uses an algorithm that utilizes the knowledge that immediately after a user passes a beacon receiver, the received power of the beacon receiver drops sharply due to the radio wave shielding effect of the human body. Determine position. Therefore, according to this position determination device, the accuracy of position determination can be maintained even if the beacon receivers are arranged with a larger interval than the conventional one. That is, it is possible to relax the placement restrictions of the beacon receivers installed in the position determination system.

(Modification 1)
In the description of the embodiment, it is assumed that the user 300 wears the beacon transmitter, but conversely, the user 300 may wear the beacon receiver. In this case, the beacon receiver 210 should be replaced with a beacon transmitter. The beacon receiver worn by the user 300 receives beacon signals from a plurality of beacon transmitters and transmits received power data groups to the position determination device 100 .

(Modification 2)
In the example of FIG. 2 described above, a total of four beacon receivers 200 were installed to cover the pass determination line with a width of 10 meters. This arrangement example is suitable for environments such as roads where it is difficult to install the beacon receiver 200 in the center of the passage determination line. On the other hand, if such restrictions do not exist, a total of two beacon receivers 200 may be installed near the midpoints of positions A1 and A2 and near the midpoints of positions C1 and C2, for example. As a result, it is possible to cover passage determination lines of the same scale as in the example of FIG. 2 while suppressing the required number of beacon receivers 200 .

It should be noted that, in this modification, it is necessary to modify the algorithm described with reference to FIGS. 11 and 12, for example. Specifically, "position A1" is read as "near the midpoint of position A1 and position A2", "position C1" is read as "near the midpoint of position C1 and position C2", and "position A2" and "position C2” can be ignored.

The above-described embodiments merely show specific examples to aid understanding of the concept of the present invention, and are not intended to limit the scope of the present invention. Embodiments can add, delete, or convert various components without departing from the gist of the present invention.

Although some functional units have been described in the above-described embodiments, these are only examples of implementation of each functional unit. For example, a plurality of functional units described as being implemented in one device may be implemented across a plurality of separate devices, and conversely, may be implemented across a plurality of separate devices. It is also conceivable that the functional units described may be implemented in a single device.

Various functional units described in the above embodiments may be realized by using circuits. A circuit may be a dedicated circuit that implements a specific function, or it may be a general-purpose circuit such as a processor.

At least part of the processing of each of the above-described embodiments can also be realized by using a processor installed in a general-purpose computer as basic hardware. A program that implements the above process may be provided by being stored in a computer-readable recording medium. The program is stored in the recording medium as an installable format file or an executable format file. Recording media include magnetic disks, optical disks (CD-ROM, CD-R, DVD, etc.), magneto-optical disks (MO, etc.), semiconductor memories, and the like. Any recording medium may be used as long as it can store the program and is readable by a computer. Alternatively, the program that implements the above processing may be stored on a computer (server) connected to a network such as the Internet, and downloaded to the computer (client) via the network.

DESCRIPTION OF SYMBOLS 100... Position determination apparatus 101... Reception part 102... Received power log storage part 103... Received power estimation part 104... Position determination part 105... Alarm part 200... Beacon receiver 210 Beacon receiver 220 Pole 230 Base 300 User

Claims (12)

(a) said plurality of first receivers of said wireless signals from a plurality of first receivers included in a first receiving device located at a first location for receiving wireless signals transmitted by a target transmitter; (b) a plurality of second receivers included in a second receiver installed at a second location for receiving said radio signal; a receiver that receives a second reception power data group representing the reception power of the radio signal at the plurality of second receivers from a receiver;
estimating the received power of the radio signal at the first location based on the first received power data group to generate a first estimated value; and generating the second estimated value based on the second received power data group an estimating unit that estimates the received power of the radio signal at the position of to generate a second estimate;
Based on comparing the first and second estimates to a first threshold , the transmitter of interest is closer to the second location than a line defined as a straight line through the first location. A position determination device comprising: When the first estimated value is less than the first threshold value and the second estimated value is greater than or equal to the first threshold value, the determination unit determines that the target transmitter is closer to the line than the line. 2. The position determination device according to claim 1, which determines that it exists on the side of said second position. The determination unit determines whether the target transmitter is the 2. The position determination device according to claim 1, which determines whether or not the line exists on the second position side. The determination unit determines that both the first estimated value and the second estimated value are below the first threshold value, the second estimated value is equal to or greater than the first estimated value, and the 4. The position determination device according to claim 3 , which determines that the target transmitter exists on the second position side of the line when the threshold value is two or more. The estimation unit
(a) searching for a maximum value of received power over a plurality of time points for each of the plurality of first receivers from the first received power data group, and offset corresponding to each of the plurality of first receivers; is added to calculate the first candidate value group, and the maximum value in the first candidate value group is determined as the first estimated value,
(b) searching the second received power data group for each of the plurality of second receivers for a maximum value of received power over a plurality of time points, and offset corresponding to each of the plurality of second receivers; is added to calculate a second candidate value group, and the maximum value in the second candidate value group is determined as the second estimated value;
The position determination device according to any one of claims 1 to 4 . A position determination device according to any one of claims 1 to 5 ;
the first receiving device including the plurality of first receivers and a first support supporting the plurality of first receivers;
the second receiver comprising the plurality of second receivers and a second support supporting the plurality of second receivers;
and
The plurality of first receivers are installed on the first support with an interval of at least half the wavelength of the radio signal from each other,
The plurality of second receivers are installed on the second support at intervals of at least half the wavelength of the radio signal from each other.
Position determination system. The plurality of first receivers are installed on the first support with an interval of at least half the wavelength of the radio signal from each other in the vertical direction,
The plurality of first receivers are installed on the first support with an interval of at least half the wavelength of the radio signal from each other in the vertical direction.
A position determination system according to claim 6 . 8. A position determination system according to claim 6 or claim 7 , wherein the target transmitter is worn on the front side of the user. (a) a first receiver representing received power at said plurality of first receivers of said wireless signals from a plurality of first receivers located at a first location and receiving said wireless signals transmitted by said transmitter; and (b) receiving the received power of the radio signal from a plurality of second receivers installed at a second location and receiving the radio signal, (c) from a plurality of third receivers located at a third location and receiving said wireless signals from said plurality of third receivers of said wireless signals; (d) receiving a third set of received power data representing received power; a receiver that receives a fourth received power data group representing received power at the receiver;
estimating the received power of the radio signal at the first location based on the first received power data group to generate a first estimated value; and generating the second estimated value based on the second received power data group estimating the received power of the radio signal at the position to generate a second estimate; and estimating the received power of the radio signal at the third position based on the third group of received power data to generate a third 3, and estimates the received power of the radio signal at the fourth location based on the fourth group of received power data to generate a fourth estimated value;
based on a comparison of the first estimate, the second estimate, the third estimate, and the fourth estimate to a first threshold, the transmitter of interest is at the first location; and a determination unit that determines whether a line defined as a straight line passing through the second position exists on the side of the third position or the side of the fourth position , A position-determining device, wherein a position and said fourth position are on the same side of said line . the first position is the farthest from the fourth position among the second position, the third position, and the fourth position;
the second position is the farthest from the third position among the first position, the third position and the fourth position;
The determination unit determines that both the first estimated value and the second estimated value are less than the first threshold value, and at least one of the third estimated value and the fourth estimated value is the determining that the target transmitter exists on the third position side or the fourth position side of the line when the threshold is equal to or greater than a first threshold;
A position determination device according to claim 9 . The determination unit determines that the target transmitter is 10. The position determination device according to claim 9, which determines whether the line exists on the third position side or the fourth position side. the first position is the farthest from the fourth position among the second position, the third position, and the fourth position;
the second position is the farthest from the third position among the first position, the third position and the fourth position;
The determination unit determines that all of the first estimated value, the second estimated value, the third estimated value, and the fourth estimated value are below the first threshold, and the third estimated value is equal to or greater than the first estimated value, the fourth estimated value is equal to or greater than the second estimated value, and both the third estimated value and the fourth estimated value are equal to or greater than the second estimated value determining that the target transmitter is present on the third position side or the fourth position side of the line when the threshold is greater than or equal to the threshold;
A position determination device according to claim 11 .

Images